1. Field of the Invention
The present invention relates to a monoclonal antibody MLS 102 specifically recognizing a cancer-associated sugar chain antigen and to a hybridoma producing it. More specifically, this invention pertains to a monoclonal antibody MLS 102 which binds specifically to cancer cell derived from human intestinal cancer tissue, in which MLS 102 binds to a sialic acid-containing sugar chain of glycoprotein but not to that of glycolipid; MLS 102 also binds to a sugar chain NeuAc.alpha.2.fwdarw.6GalNAc which is abundant in ovine or bovine submaxillary mucin. This invention also pertains to a hybridoma MLS 102 which stably grows in abdominal cavity of mouse and produces the monoclonal antibody MLS 102.
2. Description of the Prior Art
It has been recognized that on the surface of cells there are complex carbohydrates such as glycoprotein, glycolipid and proteoglycan, whose sugar chains are altered as normal cells are transformed into cancer cells. Elucidation of the mutation, that is, the change of sugar chain structure has been attempted mainly by chemically analyzing the sugar chain. However, it has become possible to obtain such a monoclonal antibody as specifically binding to a sugar chain changed on the surface of a cancer cell since 1975 when Kohler and Milstein established the method to make a hybridoma and obtain a monoclonal antibody therefrom. Recently, it has been reported that many of the monoclonal antibodies recognizing a cancer-associated antigen recognize a sugar chain and, therefore, the significance of a monoclonal antibody recognizing a cancer-associated sugar chain antigen has been pointed out and, further, some sugar chain structures of the cancer-associated antigens have been determined. It is believed that such monoclonal antibodies play a significant role in a clinical field such as a diagnosis, in an inspection of cancer therapy of cancer as well as in studies on cancer. Indeed, CA19-9, which is one type of cancer-associated sugar chain antigen, in sera of cancer patients can be assayed by using a monoclonal antibody NS19-9 specifically recognizing CA19-9 (J. Magnani et al., J. Biol. Chem. 257, 14365 (1982)), which has been effectively utilized in a diagnosis of pancreatic cancer.
Most of the conventional monoclonal antibodies bind to glycolipid on the surface of cancer cells since it is hard to prepare a monoclonal antibody binding to a sugar chain of glycoprotein. Moreover, the structures of the sugar chains recognized by the antibodies have been determined by using a glycolipid. However, it has been revealed that most of the cancer-associated sugar chain antigens appearing in sera of cancer patients are expressed on sugar chains of mucin-type glycoproteins because glycolipid is a minor component in sera. Therefore, a monoclonal antibody recognizing a sugar chain of glycoprotein has been desired as diagnostics of cancer used in a usual method employing sera.